In general, when a recorded signal on a magnetic tape is reproduced to generate a playback signal, the playback signal lacks higher harmonic components in case of a recorded signal of a distorted wave including higher harmonic components, due to various losses such as gap loss and core loss of the magnetic head, and loss due to the thickness of the magnetic tape and the space between the magnetic head and the magnetic tape. Thus, it is difficult to produce a playback output signal with the high fidelity of the recorded signal.
Especially, in case of a cassette type tape recorder wherein the magnetic tape is slowly fed and, therefore, a wave length of the recorded signal becomes substantially equal to the gap length of the playback head, it is difficult to fully correct such high frequency losses in the recording system. Also, high frequency losses which occur on reproducing the signal should be corrected in the playback system.
As the level of the recording signal becomes higher, the saturation of the magnetic tape occurs in a portion of the low frequency range and in the high frequency range at lower level than in the middle frequency range. This saturation is remarkable in the high frequency range. Accordingly, it is necessary to correct such high frequency losses upon reproducing the signal, but due to the resultant phase shift, it becomes more difficult to produce a playback signal waveform with fidelity to the recorded signal waveform.
In addition, the recorded signal of high level has a non-linear distortion at its peak due to the saturation of the magnetic tape. If the signal is recorded at lower level in order to avoid saturation of the magnetic tape, then it is difficult to produce playback signals of a desirable signal-to-noise ratio. Thus, it has been impossible to record and reproduce a distorted wave of high level with high fidelity.